BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to vibratory material-screening apparatus, and more particularly to a screen tensioning assembly for such apparatus.
2. Description of the Prior Art
Prior vibratory particulate material screening apparatus known to the present applicant has employed a screen tensioning assembly in which removal of the screen or screens required removal of threaded fasteners and disassembly of clamping and screen hold-down members. One type of such prior vibratory screen apparatus manufactured by the assignee of this application is described hereafter in connection with FIG. 1 of the drawings.
It is desirable to provide a screen hold-down and tensioning assembly for vibratory particulate material screening apparatus in which the screen or screens may be readily removed without the necessity of removing threaded fasteners and clamping and screen hold-down members.
SUMMARY OF THE INVENTION
The improved screen hold-down and tensioning assembly of the invention is adapted for use in vibratory particulate material-screening apparatus of the type which includes a frame having spaced, parallel, upstanding side panels connected by a support structure having openings therein for passing screened material therethrough. Extended area apertured screen means is provided supported on the support structure between the side panels and have opposite side edges. Means are provided for securing one side edge of the screen means to the frame and an up-turned hook portion is formed at the outer side edge. Means are provided adjacent one side panel for holding down and tensioning the screen means including a clamping member having opposite ends with one end normally engaging the hook portion and the other end normally engaging one side of the other side panel. A stud is provided having one end connected to the clamping member intermediate its ends, and its other end extending through an aperture in the one side panel. Resilient means are provided on the other end of the stud and engaging the other side of the one side panel for urging the stud in a direction to cause the clamping member to apply tension on the screen means, and means are provided for retaining the resilient means on the other end of the stud.
In accordance with the invention, means are provided on the clamping member for pivotally connecting the other end thereof to the one side panel so that the clamping member may be pivoted upwardly away from screen means to a stored position thereby to disengage the one end thereof from the hook portion. The retaining means comprises wedge means removably seated in a slot in the other end of the stud for normally engaging the resilient means whereby removal of the wedge means permits removal of the resilient means from the other end of the stud so that the clamping member may be pivoted to its stored position.
Further, in accordance with the invention, the means for securing the one side edge of the screen means to the frame comprises a down-turned hook portion formed at the one side edge of the screen means and engaging an up-standing element on the support structure, the down-turned hook portion defining a space with another element on the frame. Means are provided for removably closing and sealing against the entry of particulate material, the closing and sealing means including an upper element extending across and closing the space and a lower element seated in the space and having portions resiliently engaging the turn-downed portion and the other element. In the preferred embodiment, the screen means comprises two sections each having one side edge held-down and tensioned in accordance with the invention, the two screen sections respectively having second side edges with down-turned hook portions respectively formed thereon which define an elongated narrow space intermediate and parallel with the side panels, the down-turned hook portions respectively engaging upstanding elements on the support structure and the removable closing and sealing means of the invention closing and sealing that space.
It is accordingly an object of the invention to provide an improved screen hold-down and tensioning assembly for vibratory particulate material screening apparatus.
Another object of the invention is to provide an improved screen hold-down and tensioning assembly for vibratory particulate screening apparatus wherein the screens may be readily removed without the necessity of removing threaded fasteners and screen clamping and hold-down members.
The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1. is a fragmentary end view of vibratory particulate material screening apparatus incorporating a prior screen hold-down and tensioning assembly;
FIG. 2 is a fragmentary end view showing the improved screen hold-down and tensioning assembly of the invention;
FIG. 3 is a fragmentary top view showing the improved screen hold-down and tensioning assembly of the invention;
FIG. 4 is a fragmentary, cross-sectional view further illustrating the improved screen hold-down structure of the invention;
FIG. 5 is an end view of the hold-down member of FIG. 4 prior to assembly;
FIG. 6 is an end view showing a modification of the hold-down structure of FIGS. 4 and 5;
FIG. 7 is an end view showing a modification of the screen hold-down structure of the invention;
FIG. 8 is an end view showing another modified form of screen hold-down structure;
FIG. 9 is an end view showing a further modified form of screen hold-down structure;
FIG. 10 is a fragmentary cross-sectional view showing one embodiment of the improved screen tensioning structure of the invention in its operative position;
FIG. 11 is a fragmentary cross-sectional view showing the screen tensioning structure of FIG. 10 in its stored, screen-releasing position;
FIG. 12 is a fragmentary cross-sectional view showing a modified form of the screen-tensioning structure of the invention in its stored, screen-releasing position; and
FIG. 13 is a fragmentary, cross-sectional view of another embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 1, one type of conventional vibratory particulate material screening apparatus comprises a vibratory frame, generally indicated at 20, having spaced, parallel,
upstanding side panels 22, 24 (only one of which is shown in FIG. 1 at 22) which are connected by spaced, parallel, horizontal screen-
support members 26 which define openings (not shown) therebetween for passing screened material therethrough.
Vibratory frame 20 is supported by
spring suspensions 28 on
stationary frame 30 and is vibrated by suitable driving apparatus (not shown).
In one form of such prior vibratory screen apparatus, a pair of apertured
screens 32, 34 are provided extending between the side panels.
Screens 32, 34 are supported in a slightly upwardly arched or convex configuration by spaced
support plates 36 on
support members 26, each
support plate 36 having a
wear strip 38 thereon formed of rubber or other suitable material.
Side edge 40 of
screens 32, 34 have up-turned
hook portions 42 formed thereon and are supported on
flange members 44 extending inwardly from
side panels 22, 24.
Side edges 46, 48 of
screens 32, 34 have down-turned
hook portions 50, 52 formed thereon which respectively engage
flange members 54, 56 secured to
upper surface 58 of
support member 26. Down-turned
hook portions 50, 52 respectively define an elongated, narrow space or
slot 60 parallel with and intermediate the side panels.
In one type of such prior vibratory screen apparatus,
side edges 46, 48 of
screens 32, 34 are held-down and
space 60 is closed against the entry of particulate material by elongated center hold-down
plate member 62 which is clamped in engagement with
side edges 46, 48 of
screens 32, 34 by threaded
fasteners 64
engaging support member 26.
Spaced deflector elements 66 are secured to the upper surface of hold-down
member 62. It will be readily seen that in order to remove
screens 32, 34, it is necessary to remove threaded
fasteners 64 in order to remove hold-down
member 62.
In the aforesaid prior screen hold-down and tensioning assembly,
side edges 40 of
screens 32, 34 are held-down and tensioned by elongated
clamping plate members 68 having
edges 70 engaging
hook portions 42 of
screens 32, 34 and
edges 72 engaging the inner sides of
side panels 22, 24.
Studs 74 have
ends 76 connected to
plate members 68 intermediate their
ends 70, 72 and extend through apertures (not shown) in
side panels 22, 24. Springs 77 are positioned on
ends 78 of
studs 74 and are urged into engagement with
side panels 22, 24 by threaded
fasteners 80;
springs 77 thus urge
studs 74 in a direction to cause
plate members 68 to hold-down and
tension screens 32, 34. It will be readily seen that in order to remove and replace
screens 32, it is necessary to remove threaded
fasteners 80 and
springs 77 from
studs 74, and then to remove
plate members 68 with
studs 74 connected thereto in order to disengage
hook portions 42.
Referring now to FIGS. 2 and 3, there is shown our improved screen hold-down and tensioning assembly, the same elements being indicated by the same reference numerals and similar elements by primed reference numerals. We have found that it is not necessary to hold-down or clamp
inner side edges 46, 48 of
screens 32, 34 when
outer side edges 40 are properly held-down and tensioned, it being only necessary to close and seal
space 60 between down-turned
hook portions 50, 52. Accordingly, in accordance with the invention,
space 60 is closed and sealed by
member 82 which may take one of the forms shown in FIGS. 4 through 9 of the drawings and described below, none of which involve attachment by means of threaded fasteners.
In accordance with the invention, as shown in greater detail in FIGS. 10 through 12 of the drawings and described below, clamping plates 68' have spaced, relatively
narrow pivot members 84 secured to end or
side edges 72 which permit clamping members 68' to be pivoted upwardly away from
screens 32, 34 to a stored position in which ends or
side edges 70 are disengaged from up-turned
hook portions 42.
Resilient compression units 79 are retained on ends 78' of
studs 74 by
removable wedge members 86. Thus, in order to remove and replace
screens 32, 34, it is only necessary to pry closing and sealing
member 82 out of
space 60, to remove
wedges 86 and
compression units 79, and to pivot clamping plates 68' to their stored positions, as best seen in FIG. 11, it being observed that removal and replacement of
screens 32, 34 does not require removal of any threaded fasteners nor removal of hold-down and tensioning members.
Referring now to FIGS. 4 and 5, in the preferred embodiment, closing and sealing
member 82 comprises an elongated member formed of extruded rubber or other suitable resilient material.
Member 82 has an upper closing and sealing
portion 88 which extends across
ends 46, 48 of
screens 32, 34 and engages the same to seal opening 60.
Upper portion 88 preferably has an outwardly or convexly curved
outer surface 90 for deflecting particulate material onto
screens 32, 34.
Member 88 has integrally formed
leg portions 92, 94 defining
slot 96 therebetween and resiliently engaging down-turned
hook portions 50, 52 of
screens 32, 34 thereby holding
member 82 in assembled position, as shown in FIG. 4. As shown in FIG. 5,
member 82 is preferably initially extruded with
lower ends 98, 100 of
leg portions 92, 94 spaced-apart to define
opening 102 thus providing the requisite resilience for
leg portions 92, 94 to permit resilient engagement with down-turned
hook portions 50, 52 of
screens 32, 34.
It will be observed that
member 82 cannot vibrate out of
space 60 during vibratory operation of the screening apparatus by virtue of the enlarged, wedge-shaped configuration of
leg portions 92, 94 which are wider, at their widest extremities, even with ends 98, 100 abutting as shown in FIG. 4, than the width of
space 60. It will be seen that the somewhat wedge-shaped configuration of
member 82 permits it to be driven into
space 60 while the resilient characteristic of
member 82 permits it to be removed from
space 60 by prying with a suitable implement, such as a large screwdriver.
Referring now to FIG. 6, in which like elements are indicated by like reference numerals, if tighter engagement of
leg portions 92, 94 of
member 82 with turned-down
hook portions 50, 52 of
screens 32, 34 is desired,
elongated tube 104 of rubber or other suitable material is inserted into
slot 96 of
member 82 thereby to spread
leg portions 92, 94 causing tighter engagement with
hook portions 50, 52 after assembly. It will be readily understood that the necessitity for using
tube 104 depends upon the durometer of the material used for
member 82;
tube 104 may be needed when low durometer material is used whereas, it may not be needed with higher durometer material. It will be further be understood that
element 104 may be solid rather than tubular.
Referring now to FIG. 7, member 82' may be formed of solid, extruded resilient material without
slot 96 of the embodiment of FIGS. 4 through 6.
Referring to FIG. 8,
member 82" may have
upper portion 88 formed of extruded, resilient material with
leg portions 92", 94" formed of suitable spring metal, such as spring steel, adhered thereto or molded therein. Referring to FIG. 9,
member 82"' may be integrally formed of suitable spring metal, as shown.
Referring now to FIGS. 10 and 11, each
pivot member 84 comprises an elongated bar member having one
end 106 secured to end 72 of clamping plate member 68', as by welding, as shown.
Member 84 extends through
aperture 108 in
side panel 22 and has up-turned
hook portion 110 formed at its other end. Stud 74' extends through
opening 112 in clamping plate member 68' intermediate its ends 70, 72, and
head 76 thereof is held in engagement with clamping plate 68' by
pin 114. The shank of stud 74' extends through
aperture 116 in
side panel 22 below
aperture 108, and through
opening 118 in bearing
member 120 secured to the
outer side 138 of
side panel 22, as by welding as shown. Annular
resilient compression unit 79 comprises a part-
spherical bearing member 122, one-piece annular
resilient member 81 formed of suitable material such as rubber or neoprene, and
annular plate member 132.
Bearing member 122 slidably mounted on the shank of stud 74' engages the part-spherical socket in bearing
member 120 and its integrally formed disc-shaped
portion 124 is bonded to one end of
resilient member 81.
Wedge member 86 has small and
large ends 126, 128, and is removably seated in
slot 130 in end 78' of stud 74' engaging
plate 132 which is bonded to the other end of
resilient member 81.
It will be seen that
unit 79 is a unitized element thus eliminating risk of dropping washers, springs, etc. It will further be seen that with
wedge member 86 wedged in place,
unit 79 will be in compression thus urging stud member 74' in the direction as shown by
arrow 134 thereby to urge clamping member 68' in that direction so that its
end 70 engages
hook portion 42 of
screen 32 and its
end 72 engages
inner surface 139 of
side panel 22 to apply tension thereon. It will be understood that
wedge 86, once driven in place, compresses
unit 79 maintaining tension on
screen 32 thus accommodating expansion and contraction of the screen. While use of
compression units 79 is preferred, it will be understood that the coil springs 77 of FIG. 1 may be employed.
Referring now additionally to FIG. 11, in order to remove and replace
screen 32,
wedge 86 is driven out of
slot 130 in end 78' of stud 74' thus permitting
compression unit 79 to be removed from end 78' of stud 74'.
Hook portion 110 of
pivot member 84 forms a pivot for clamping plate member 68' permitting it to be pivoted upwardly away from
screen 32 to a stored position, as shown in FIG. 11, with
end 70 disengaged from
hook portion 42. It will be observed that during pivoting, end 136 of
hook portion 110 engages
outer surface 138 of
side panel 22.
Wedge member 86 has
notch 140 formed in its edge
adjacent end 126.
Notch 140 is adapted to engage
edge 142 of
side panel 22 which forms
aperture 116 so that
wedge member 86 cooperates with
ends 144, 146 of
slot 130 to hold stud 74' and clamping member 68' in the stored positio, as seen in FIG. 11.
It will now be seen that
screen 32 can be removed or replaced by merely pivoting clamping member 68' to its stored position without requiring removal of threaded fasteners and removal of the clamping member from the frame. While wedges similar to
wedge members 86 have previously been used in screen tensioning assemblies, to the best of my knowledge they have no heretofore been used in conjunction with compression springs for retaining a pivoted clamping member in screen-tensioning position.
Referring now to FIG. 12, in which like elements are indicated by like reference numerals and similar elements by primed reference numerals,
stud 74" has
annular shoulder 148 formed thereon which is engaged with
edge 150 of opening 116 in
side panel 22 thereby to hold
stud 74" and clamping member 68' (FIG. 11) in the open, stored position.
FIG. 13 illustrates another embodiment of this invention. Like numerals indicate like parts and similar parts have the same reference numerals with the suffix "a" added. In this embodiment, the
slot 60a is disposed between
flange member 54 and one
side panel 22. The
screen 32 having a down-turned
hook portion 50 engaged with the
flange 54 is stretched toward the
other side panel 22 and is suitably secured into place, for example, by means of clamping
plates 68 or 68' and the associated assembly as shown in FIGS. 1 and 2. A closing and sealing
member 82a formed substantially the same as
member 82 of FIGS. 4 and 5 is inserted in the
slot 60a, this slot being defined between the down-turned
hook portion 50 of
screen 32 and a half-
round bar 200 welded to the inside of the
side panel 22. The
bar 200 extends parallel to the
flange 54 but is spaced therefrom as shown.
The closing and sealing
portion 88a of the
member 82a is formed differently than the counterpart portion of member 82 (FIGS. 4 and 5) in that the
upper surface 202 thereof is inclined upwardly and away from the
screen 32 to a point of engagement with the
side panel 22. Thus, particulate material can gravitate down the sloped
surface 202 and onto the
screen 32.
Other closing and sealing members according to the embodiments of FIGS. 6-8 may be used instead of the
particular member 82a so long as the upper surface thereof is sloped like
surface 202. While a particular slope is shown in the drawings, it is to be understood that the shape of the surface may vary so long as it inclines downwardly toward
screen 32 so as to divert any particulate material thereon toward the
screen 32.
In other respects, the closing and sealing
member 82a conforms to the structure and function described in connection with FIGS. 4 and 5 as well as the other embodiments of FIGS. 6-8.
While there have been described above the principles of this invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of the invention.